Are people comfortable giving up even more privacy to help boost retailers' bottom lines? That's the aim of Nordstrom's use of Euclid -- a service that lets retailers track individuals' movements through their smart phones' in-store WiFi connections. But Nordstrom is quick to point out that the tracking is anonymous, so no worries.

Nordstrom is among 100 Euclid customers that the New York Times reports have "already tracked about 50 million devices in 4,000 locations."

Nordstrom is using Euclid's technology in 17 stores around the country, according to CBS-11. A Nordstrom spokesperson, Tara Darrow, told CBS-11 that "sensors within the store collect information from customer smartphones as they attempt to connect to Wi-Fi service. The sensors can monitor which departments you visit and how much time you spend there. However, the sensors do not follow your phone from department to department, nor can they identify any personal information tied to the phone’s owner."

Darrow said that this anonymous information helps Nordstrom serve its customers better. By giving Nordstrom "a better sense of customer foot traffic” Euclid will help Nordstrom to "increase staffing during certain high-traffic times or change the layout of a department," according to her interview with CBS-11.

Nordstrom has been doing this since October 2012 and it posts signs at store entrances notifying consumers that they can opt out by turning off their phones. At another chain, spokesman Stephen Holmes says, "We once tested [Euclid] in a handful of stores but no longer use it."

In two interviews with Euclid's founder and CEO, Will Smith, I learned that the Stanford grad comes from a family of retailers and that the company -- he likened it to Google Analytics for retailers -- grew at an eye-popping 11,949% in 2012.

Smith said that Euclid charges $200 per month for each sensor — the device that tabulates the foot traffic in the store. The sensor senses consumers’ WiFi signal, sends the data to the cloud, and creates an online dashboard for store managers.

That light-speed growth at Euclid is not revenue, but tracking activity. Specifically, Smith told me that the number of its events per day — Euclid’s count of a device like an iPhone, in a specific location, at a point in time (it samples about once a minute, depending on WiFi broadcast frequency) – had increased at a 11,949% annual rate from a million at the beginning of 2012 to 3 billion as of January 2, 2013.

Euclid can help retailers track sales to people on the floor — decomposing revenue into three parts — the number of people who walk into the store, the percentage of those people who buy (the conversion rate), and the average size of those buyers’ purchases (the basket size).

Smith explained that Euclid helps stores boost revenues in two ways. First, it keeps track of the proportion of people who walk by the store window and can help retailers measure how changes in the window displays boost the number of people who walk in. If more people walk in and the conversion rate stays constant, that means more revenues.

Second, Euclid can help measure how long people stay inside the store. And Smith has observed that the longer someone stays in the store, the larger their average basket size. Thanks to Euclid’s data on in-store traffic, floor managers can make more accurate predictions of the ups and downs of traffic during the week and at different times of day.

These better predictions allow floor managers to decide when they need to put more sales people on the floor to handle a surge in traffic and when there is likely to be a lull in potential buyers — so the floor can safely assign fewer people to handle the diminished demand.

The result of this is that Euclid helps stores to better match the supply of sales people with the demand for their services. This means that when many customers are eager to buy, the retailer will close more sales and when fewer potential customers are on the floor, the retailer can cut its costs.

In January, Smith also told me that hedge funds were desperate to get their hands on the names of its publicly-traded customers so the investors could buy stock in them. Now one of those cats is out of the bag.

If you don't like the way Nordstrom is tracking your in-store movements, you can make the world a little less profitable for hedge funds by powering down your smartphone while you're shopping there.

Unfortunately, if you mind videos being taken of your movements once you're outside the store, you are out of luck.

Update. At 4:21 pm ET, Darrow emailed me that Nordstrom is no longer using Euclid. According to her statement: "Our Euclid test has concluded. Euclid sensors are no longer collecting any data in our stores as of [May 8, 2013]."

She continued, "We'd had Euclid in select stores since September and have said all along this was a test. We felt like we learned a lot and got great feedback from our customers. After 8 months it made sense to end the test."

She concluded, "This type of technology is just one way that we can learn about things like customer foot traffic and find more opportunities to improve the service we offer them. We’re going to continue to try new things and we’ll incorporate what we heard and learned here into other things we try out in the future."